Agito RoamAnywhere Solution Ties Mobile Phones, Corporate Systems

By Andrew Garcia |
Posted 2008-11-17

Agito RoamAnywhere Solution Ties Mobile Phones, Corporate Systems

The Agito Networks RoamAnywhere Mobility solution does an excellent job of
wedding a user's mobile phone to the corporate PBX, allowing users to
seamlessly place and receive calls using their business extensions and to
leverage the corporate directory no matter where they might be or what network
they are connected to.

With its excellent Wi-Fi fingerprinting technology, Agito's fixed mobile
convergence solution efficiently handles the transitions from WLAN to cellular
resources, allowing a business to save money on mobile minutes without
requiring the user to do anything special. With Version 2.0 of the
RoamAnywhere solution, which was released in October, Agito added
mission-critical high availability as an option and layers of additional
security features so remote users can leverage Wi-Fi network connections as
well.

Agito's RoamAnywhere solution consists of two parts: the RoamAnywhere client,
which can be installed on an assortment of smart phones running Windows Mobile
6 (both Standard and Professional) or the Nokia E- and N-Series devices, running
Symbian; and the RoamAnywhere Mobility Router, which sits in the corporate data
center and works in concert with the PBX.

Agito offers two versions of the Mobility Router, with options for high
availability on the larger solution. The smaller of the two, the
RoamAnywhere 2000, supports up to 100 users for a list price of $24,195. The
bigger box, the RoamAnywhere 4000, supports up to 1,000 users, though I priced
it out for 500 users, which would cost $109,995.

The RoamAnywhere 4000 can also be paired with a second appliance for high
availability. The second unit comes with a bit of a discount when bought
together for redundancy-the pair of RoamAnywhere 4000s costs $186,192 when
licensed for 500 users.

The devices operate in an active/passive relationship, where the second one
will take over call routing duties if the first fails. In tests I found
active calls would continue uninterrupted if I pulled the plug from the primary
unit (although this is not surprising given the system's architecture).

Agito maintains both a trunk-side and a line-side relationship with the
PBX. In most cases, Agito-enabled phones conduct signaling duties in
conjunction with the Mobility Router, while the call payload goes directly to
the party on the other end, if end-to-end SIP (Session Initiation Protocol), or
to the PBX for calls with the PSTN (Public Switched Telephone Network). Only
when the smart phone is connected to a foreign Wi-Fi network will the call
payload traverse touch the Mobility Router, requiring the trunk-side
integration.

With the phones actively communicating with the PBX, a line-side
relationship has the potential to allow a richer subset of the PBX features to
an FMC client. However, this type of
integration also requires much work from Agito to ensure that supported devices
continue to work when a PBX is patched or upgraded, so customers need to talk
with Agito before performing upgrades on the PBX itself.

Agito is prequalified to work with Asterisk, Avaya, Cisco Systems, Microsoft
and Nortel IP PBXs, but I found Avaya and Cisco were best supported, as I could
bulk-configure extensions on the PBX from Agito's Web-based configuration
pages. Testing Agito in conjunction with a Cisco Call Manager, I found
that depending on the configuration, the administrator will need to make
several changes to PBX configuration-for instance, to twin the mobile phone with
a desk phone, allowing both to ring simultaneously.

Agito is also prequalified to work with several enterprise-grade wireless
network solutions, including solutions from Cisco, Aruba Networks, Aerohive
Networks, Meru Networks, and Belden's Trapeze Networks. However, the
Mobility Router should work with most wireless networking solutions (802.11g or
better), although Agito recommends the network support the WMM spec and 802.11i
Enterprise with key precaching or
pre-shared key. Agito does offer further integrations with both Cisco and
Aruba WLAN controllers to leverage those companies' adaptive radio management
techniques.

Testing RoamAnywhere Mobility

Agito utilizes several data sources to help make the decision when to roam
from the cell network and back to Wi-Fi. At the network level, the
Mobility Router can tap into data culled by Cisco's Mobility Services
Engine. On the client side, the Mobility client utilizes typical metrics
like signal strength, but also leverages location-by comparing a device's
location to a series of fingerprints (signal strengths of all detected nearby
access points and some cell tower information taken from a designated spot)
taken by a system administrator at a building's egress points when the solution
is rolled out.

I took fingerprints by loading a special calibration application on a
supported smart phone, recording three or four measurements just outside each
exit point. From the calibration tool, I could measure the accuracy of the
fingerprint, walking back and forth through the threshold to ensure that the
roam happened where it should. Then I could upload the fingerprint to the
Mobility Router, where I could then apply the fingerprint to a location policy
object.

In the background, the Mobility Router also performs a series of heuristics
against the fingerprint, to alter fingerprint settings according to known Wi-Fi
detection capabilities of different phones than the one used during calibration
process. In this way, Agito tries to make one calibration work for every
supported device, no matter the differences in radio power or antenna
position. The fingerprint also captures some data about the cellular
network, allowing Agito to save a bit of battery life for the client because
the device won't start scanning Wi-Fi until it detects the device is associated
with a cell tower known from the fingerprint.

I tested with two devices-an AT&T Tilt and a Nokia E71-and I indeed
found that the fingerprint taken with the E71 worked as expected with the Tilt
as well, causing seamless handovers as I walked in and out of the
building. However, I also found that with both devices, as I exited the
test facility, some unexpected roams back to the Wi-Fi network would also occur
well outside of the building if I loitered around for a few seconds.

To counter tricky areas where Wi-Fi bleedsoutside the corporate walls, Agito
lets administrators fine-tune handover settings for each location in the
network. In this way, I could adjust the RSSI (Received Signal Strength Indicator)
threshold to ensure that such roams from cell to Wi-Fi only occur inside the
building, and then create distinct settings for each building as necessary.

The client experience was drastically different between the Nokia and
Windows Mobile iterations. On Windows Mobile, Agito has painted its dial
application into the native Windows Mobile dialer, whereas the Nokia devices
have a separate dial application (called RADialer). This meant that the
process of placing calls, looking up corporate contacts from Active Directory
or changing forwarding rules was sufficiently different enough between the two
that it was a bit confusing to use both.

I also noted a significant difference in call quality on the two
devices. In both cases, I found calls on the Wi-Fi network sounded
significantly clearer than calls placed over the GSM network. This also
made it fairly obvious to detect when I switched between networks, even if
there were no temporary dropouts or garbles. However, the Windows Mobile
devices sounded clearer and more distinct than the Nokia phones over Wi-Fi,
likely due to the use of the outstanding codecs from GIPS as part of the
Windows Mobile client.

Both sets of devices allow the user to place calls in either personal
mode-using the cell phone's number-or in corporate mode, using the PBX
extension. This dual persona allows the user connected to an enterprise call to
accept a second personal call as well, no matter if the first call is connected
via Wi-Fi or cellular. The system administrator does have the option of
blocking the use of personal mode via central policy.

Version 2.0 of the Mobility Router also introduces additional security
measures for calls coming in over remote, potentially unknown Wi-Fi
networks. When a client connects to a foreign Wi-Fi network, the Agito
client automatically engages Secure Remote Voice-in essence, an application
layer SSL [Secure Sockets Layer] VPN. The
client uses a split tunnel: The encrypted connection to the Mobility Router
protects call data, signaling and directory lookups from prying eyes, while any
Web browsing or other network activity goes directly to the Internet.

Administrators can further tune Secure Remote Voice to only work from
approved remote networks such as the user's home network.

Secure Remote Voice costs an additional $6,049 for 100 users on the
RoamAnywhere 2000, or an additional $27,499 for 500 users on a RoamAnywhere
4000.